Search

What's New in 3D Printing, Part II: the Hardware

This is the second article in what will be a four-part series on the
current state of 3D printing compared to how things were three years
ago when I wrote my first series on 3D printing. Of course, this
is Linux Journal, so the focus will be on Linux and
open-source-specific aspects in 3D printing. I won't dwell much on
proprietary products. In my last article, I gave a general overview on
the state of 3D printing; in this one, I focus on the
hardware side.

If you were to compare 3D printers three years ago to today, probably the
first thing you would notice is just how polished and consumer-focused
the overall look of the machines are now. Three years ago, most printers
were based off the RepRap line of 3D printers. They had a hobbyist look,
with 3D-printed gears and other parts combined with nuts and bolts you
could get from the hardware store. Those printers that didn't consist of
a series of threaded and smooth rods for their structure were made from
laser-cut wood. The focus was much more on community and sharing designs
freely to improve the quality of the printers as rapidly as possibly while
still using parts easily purchased from a hardware store or on-line. Many
of the commercial 3D printer offerings at the time also were some form of
a RepRap printer sold pre-assembled and calibrated with some refinements
and improvements, plus support from the company if anything went wrong.

Fast-forward to today, and the selection of 3D printers is widely
different. As the focus has shifted from the hobbyist to the consumer,
you see modern designs that hide away the electronics and wiring, forgo
laser-cut wood for painted metal and acrylic cases, and look more like
something you'd put on a desk in your office than a work bench in the
garage. It reminds me a lot of the early attempts to polish the Linux
desktop to appeal more to the end user, and both changes have received a
similar backlash from the original community.

One of the best examples of
the difference between old and new is a comparison between the original
Ultimaker and the current Ultimaker 2. The original has the classic boxy
laser-cut wood case, while the modern printer has a frosted acrylic case.

Figure 1. The Original Ultimaker

Figure 2. The Current Ultimaker 2

So, what caused this shift in focus? A number of factors are involved,
but I'd argue it was the success of the original Printrbot Kickstarter
campaign, itself a RepRap design modified to be more affordable and
aimed at schools and the end consumer, that attracted many entrepreneurs
to say "I can do that" and start their own 3D printer companies. In a
world of $2,000 Makerbots or $800 RepRap kits, a $500 3D printer grabbed
the attention of a whole new group of users (including yours truly) who
couldn't quite justify $800 for a kit that wasn't guaranteed to work after
many hours of assembly.

You can see the changes in the Printrbot line
itself. The original printer was much like a RepRap with many 3D-printed
parts and a wooden print bed with an optional heated bed. The immediate
follow-up to that printer traded some of those parts for laser-cut wood
to speed up manufacturing. Compare that to the modern Printrbot line,
which are all shipped assembled, all made with painted metal frames and
machined metal print beds, and still are around the same price as the
original assembled Printrbots.

Figure 3. The Original Printrbot

Figure 4. The Current Printrbot Simple Metal

One unfortunate trend in modern 3D printers is the absence of open
design files. Years ago, most of the major 3D printers fully shared all
of the hardware design files; thus, if you were so inclined, you could
build
your very own 3D printer with your own self-sourced parts. Makerbot's
announcement that it no longer would share the design files for its
Replicator line created quite a bit of outrage in the community, but
despite that, a number of other 3D printing companies followed suit. That
said, there still are some notable 3D printing companies that continue
the open-source ethos and share their design files, such as Ultimaker,
Lulzbot and Printrbot, all offering their hardware design files either
along with the introduction of a new product or within a few months.

Extruders

Extruder design is another area that has seen a lot of innovation during
the past three years. The extruder is the part of the 3D printer that
feeds plastic filament into a hot end where it is melted and printed
out. Three years ago, many printers adopted some variation of the Wade's
extruder design, which used a stepper motor connected to a small gear that
powered a larger gear connected to a bolt with teeth that would grip onto
the filament. The concept of multiple extruders on a single printer was
still in the early prototype phase, and most extruders used 3mm filament.

These days, just about every printer has its own custom extruder design
and hot end. Many extruders have shifted to a direct drive system where
the stepper motor has a gear directly attached to it that feeds filament
into the hot end, and 1.75mm filament is starting to become the norm. Many
of the most popular printers now offer dual extruders as an upgrade
option. With dual extruders, a printer can feed two different colors of
filament or even two different filament types into the same print. This
not only allows you to print multiple colors at the same time, but it also allows
you to print support material out of a water-soluble filament instead
of having to snap or cut it off of the print when it's finished. In the
past, many hot ends were ceramic and used a teflon tube inside to feed
the filament from the top of the hot end into the heated area before
it was extruded. With the new interest in more exotic filaments, some
of which require higher temperatures than PLA or ABS require, all-metal
hot ends are starting to become popular as they can be heated past the
limits imposed by a teflon tube.

Calibration Improvements

Since most 3D printers three years ago were geared toward hobbyists who
likely built the printer as a kit, a large amount of calibration and
tinkering were assumed to be part of the fun. Everything from calibrating
potentiometers for your stepper motors to the levelness of your print
bed to the height your Z axis above the print bed required a screwdriver,
feeler gauges, calipers, locking bolts, and trial and error. Often moving
the printer from one location to another would throw off your calibration,
so you had to budget a whole new round of adjustments.

With the focus shifting from hobbyists to consumers, a lot of attention
has shifted to making calibration simpler. First, the majority of printers
sold today are assembled and calibrated before they show up at
your door. Second, some printer models, such as the Printrbot line,
include a magnetic sensor that can sense when it is close to a metal
print bed. This sensor then can be used with an automatic calibration
routine to measure the distance from the print bed along three corners
and then level the print bed in software. Instead of adjusting a screw
above a Z-axis endstop to change the Z-axis height above the bed, the
Printrbot line takes advantage of the metallic sensor to get close to
the print bed and allows you to enter a number in the printer's settings
to move the Z axis higher or lower by a fraction of a millimeter. Once
this value is set, you no longer have to calibrate your Z axis unless you
tinker with or remove the hot end. Although these days the stepper motor
currents already were calibrated when the printer was being assembled,
if you find you do need to adjust them, some printer boards even allow you to
adjust that in software instead of with a screwdriver.

New Materials

One of the most exciting areas of innovation in 3D printing today is in
the materials you can use. Three years ago, your material choices
basically were limited to PLA and ABS plastic. Today, in addition to a much
greater variety of colors for PLA and ABS (including glow-in-the-dark),
there are a number of more exotic plastics, such as PVA (water-soluble), and
a number of different nylon filaments that provide different strength and
flexibility profiles. There also are new flexible filaments
like Ninjaflex, Filaflex and Ninjaflex Semiflex that let you print with
a material that acts much more like rubber than plastic and can be used
for sandals, toy car tires or cell-phone cases.

Most recently, a number of exotic PLA material blends have appeared where
traditional PLA filament is blended with tiny fragments of other materials
including wood, bamboo, carbon fiber, iron, copper, brass and
bronze. Each
of these materials more or less extrudes like PLA, but the finished product
has properties of the blended material. For instance, wood and bamboo
filaments look quite a bit like wood grain with each layer and can be
stained with wood stains. The metallic filaments each can be polished and
overall given post-processing treatments like metal, and they can be polished
with steel wool or in a rock tumbler. For instance, the copperfill
filament I have can be polished, and the finished product even smells
like a penny. Iron filament even can react with magnets. Unfortunately,
since PLA still is used to bind the metallic dust together, products
made with these materials don't have the strength of the pure metal, so
the applications are more appropriate for jewelry or busts and less for
metal bars or gears. If you need strength, it's still better
to look into one of the other plastics like ABS or Nylon.

As you can see, 3D printing is a rapidly moving technology, and a lot has
changed in the past three years. I know this article has veered a bit
away from the traditional Linux-based content you normally see in this
space, so next month, I'll make up for it with a look into the innovations
in open-source 3D printing software that interfaces with this hardware.

Kyle Rankin is a Tech Editor and columnist at Linux Journal and the Chief Security Officer at Purism. He is the author of Linux Hardening in Hostile Networks, DevOps Troubleshooting, The Official Ubuntu Server Book, Knoppix Hacks, Knoppix Pocket Reference, Linux Multimedia
Hacks and Ubuntu Hacks, and also a contributor to a number of other O'Reilly books. Rankin speaks frequently on security and open-source software including at
BsidesLV, O'Reilly Security Conference, OSCON, SCALE, CactusCon, Linux World Expo and Penguicon. You can follow him at @kylerankin.